Light source device and light polarizing element

Abstract

A light source device, comprising a light guide ( 3 ) having two light incident surfaces opposed to each other for receiving incident light radiated from a primary light source and a light outgoing surface ( 33 ) for emitting the incident light and a light deflection element ( 4 ) disposed adjacent to the light emitting surface side of the light guide, the light deflection element ( 4 ) further comprising a light receiving surface ( 41 ) for receiving incident light and a light emitting surface ( 42 ) positioned on the opposite side thereof and emitting the incident light, wherein a plurality of elongated prisms formed of two prism faces are disposed on the light receiving surface ( 41 ) generally parallel with each other, the prism surfaces are formed of at least two faces ( 46, 47, 48, 49, 50, 51 ) with different inclination angles, and the inclination angles are larger for the faces positioned nearer the light emitting surface ( 42 ).

1. A light source device comprising primary light sources, a light guide having two light incident surfaces opposed to each other and adapted to receive light emitted from said primary light sources, and a light outgoing surface for guiding and emitting the received light, and a light deflection element disposed adjacent to said light guide on a light outgoing surface side thereof,
 wherein said light deflection element has a light receiving surface for receiving the light and a light emitting surface located on a side opposite to said light receiving surface for emitting the received light, said light receiving surface has a plurality of elongated prisms arrayed substantially parallel to each other and each composed of two prism faces, and each of said prism faces is formed by at least two faces having different inclination angles wherein one of said faces located closer to said light emitting surface has a larger inclination angle and a difference between an inclination angle of one of said faces closest to said light emitting surface and an inclination angle of the other one of said faces farthest from said light emitting surface is 15 degrees or less. 
 
     
     
       2. A light source device according to  claim 1 , wherein at least one of said faces is a flat face. 
     
     
       3. A light source device according to  claim 2 , wherein all of said faces are flat faces. 
     
     
       4. A light source device according to  claim 3 , wherein said faces are at least three flat faces. 
     
     
       5. A light source device according to  claim 1 , wherein at least one of said faces is a convex curved face. 
     
     
       6. A light source device according to  claim 5 , wherein all of said faces are convex curved faces. 
     
     
       7. A light source device according to  claim 5 , wherein said faces are at least one flat face and at least one convex curved face. 
     
     
       8. A light source device according to  claim 7 , wherein said faces are at least two flat faces and at least one convex curved face. 
     
     
       9. A light source device according to  claim 5 , wherein at least two of said faces are convex curved faces having mutually different shapes. 
     
     
       10. A light source device according to  claim 5 , wherein a ratio (r/P) between a radius of curvature (r) of said convex curved face and a pitch (P) of said elongated prisms is 2 to 50. 
     
     
       11. A light source device according to  claim 5 , wherein at least one of said convex curved faces is a noncylindrical surface. 
     
     
       12. A light source device according to  claim 1 , wherein the number of said faces formed in a region having a height h from a vertex portion of said elongated prism is at least two and, when a height of said elongated prism is given as H, h/H is 10% or more. 
     
     
       13. A light source device according to  claim 1 , wherein a ratio (d/P) of a maximum distance (d) between said faces and a virtual flat surface which is defined by connecting a vertex portion and a bottom portion of said elongated prism to each other relative to a pitch (P) of said elongated prisms is 0.4 to 5%. 
     
     
       14. A light source device according to  claim 1 , wherein a vertical angle of said elongated prism is 35 to 80 degrees. 
     
     
       15. A light source device according to  claim 1 , wherein one (α) of allocated angles of a vertical angle of said elongated prism is 25 to 40 degrees, and the other allocated angle (β) is 25 to 40 degrees. 
     
     
       16. A light source device according to  claim 1 , wherein one (α) of allocated angles of a vertical angle of said elongated prism and the other allocated angle (β) differ from each other. 
     
     
       17. A light source device according to  claim 1 , wherein, in a luminance distribution of outgoing light emitted from said light deflection element, an outgoing light distribution width (θ 70 ) where a luminance becomes 70% of a peak luminance is 10 degrees or more. 
     
     
       18. A light source device according to  claim 1 , wherein, in a luminance distribution of outgoing light emitted from said light deflection element, a ratio (θ 20 /θ 90 ) between an outgoing light distribution width (θ 90 ) where a luminance becomes 90% of a peak luminance and an outgoing light distribution width (θ 20 ) where a luminance becomes 20% of the peak luminance is 5 or less. 
     
     
       19. A light source device according to  claim 1 , wherein a light diffusion element is adjacently disposed on the light emitting surface of said light deflection element. 
     
     
       20. A light source device according to  claim 19 , wherein said light diffusion element is configured such that a full width half maximum of an outgoing light intensity distribution is 1 to 13 degrees when parallel light is incident thereon. 
     
     
       21. A light source device according to  claim 19 , wherein a haze value of said light diffusion element is 8 to 82%. 
     
     
       22. A light source device according to  claim 19 , wherein an average inclination angle of at least one of surfaces of said light diffusion element is 0.8 to 12 degrees. 
     
     
       23. A light source device according to  claim 19 , wherein said light diffusion element is configured such that a full width half maximum of an outgoing light intensity distribution has an anisotropy when parallel light is incident thereon. 
     
     
       24. A light source device according to  claim 19 , wherein said light diffusion element is configured such that a maximum full width half maximum of an outgoing light intensity distribution is 1.1 times a minimum full width half maximum or greater when parallel light is incident thereon. 
     
     
       25. A light deflection element comprising a light receiving surface for receiving light and a light emitting surface located on a side opposite to said light receiving surface for emitting the received light,
 wherein said light receiving surface has a plurality of elongated prisms arrayed substantially parallel to each other and each composed of two prism faces; and each of said prism faces is formed by at least two faces having different inclination angles wherein one of said faces located closer to said light emitting surface has a larger inclination angle and a difference between an inclination angle of one of said faces closest to said light emitting surface and an inclination angle of the other one of said faces farthest from said light emitting surface is 15 degrees or less. 
 
     
     
       26. A light deflection element according to  claim 25 , wherein at least one of said faces is a flat face. 
     
     
       27. A light deflection element according to  claim 26 , wherein all of said faces are flat faces. 
     
     
       28. A light deflection element according to  claim 27 , wherein said faces are at least three flat faces. 
     
     
       29. A light deflection element according to  claim 25 , wherein at least one of said faces is a convex curved face. 
     
     
       30. A light deflection element according to  claim 29 , wherein all of said faces are convex curved faces. 
     
     
       31. A light deflection element according to  claim 29 , wherein said faces are at least one flat face and at least one convex curved face. 
     
     
       32. A light deflection element according to  claim 31 , wherein said faces are at least two flat faces and at least one convex curved face. 
     
     
       33. A light deflection element according to  claim 29 , wherein at least two of said faces are convex curved faces having mutually different shapes. 
     
     
       34. A light deflection element according to  claim 29 , wherein a ratio (r/P) between a radius of curvature (r) of said convex curved face and a pitch (P) of said elongated prisms is 2 to 50. 
     
     
       35. A light deflection element according to  claim 29 , wherein at least one of said convex curved faces is a noncylindrical surface. 
     
     
       36. A light deflection element according to  claim 25 , wherein the number of said faces formed in a region having a height h from a vertex portion of said elongated prism is at least two and, when a height of said elongated prism is given as H, h/H is 10% or more. 
     
     
       37. A light deflection element according to  claim 25 , wherein a ratio (d/P) of a maximum distance (d) between said faces and a virtual flat surface which is defined by connecting a vertex portion and a bottom portion of said elongated prism to each other relative to a pitch (P) of said elongated prisms is 0.4 to 5%. 
     
     
       38. A light deflection element according to  claim 25 , wherein a vertical angle of said elongated prism is 35 to 80 degrees. 
     
     
       39. A light deflection element according to  claim 25 , wherein one (α) of allocated angles of a vertical angle of said elongated prism is 25 to 40 degrees, and the other allocated angle (β) is 25 to 40 degrees. 
     
     
       40. A light deflection element according to  claim 25 , wherein one (α) of allocated angles of a vertical angle of said elongated prism and the other allocated angle (β) differ from each other.